System and apparatus for determining the listening habits of wave signal receiver users



2,652,310 LISTENING ERS s. A. SCHERBATSKOY Sept. 15, 1953 V SYSTEM AND APPARATUS FOR DETERMINING THE HABITS OF WAVE SIGNAL RECEIVER US 4 Sheets-Sheet 1 Filed Oct. 24, 1947 IIII [N y a o V m mmhms MMQQ Sept. 15, 1953 s. A. SCHERBATSKOY 2,652,310 SYSTEM AND APPARATUS FOR DETERMINING THE LISTENING HABITS 0F WAVE SIGNAL RECEIVER USERS Filed Oct. 24, 1947 4 Sheets-Sheet 2 1. 7 TIME B Serge A. Scherbutskoy Mil/21W Sept. 15, 1953 s. A. SCHERBATSKOY 1 SYSTEM AND APPARATUS FOR DETERMINING THE LISTENING HABITS OF WAVE SIGNAL RECEIVER USERS Filed Oc t. 24, 1947 4 Sheets-Sheet 4 NIH!!! I? 2 2 2 2 2 7 ME 101' A was 6 7 T819 m e TH TH A If+ o v O 2 5 2 I I I I FIG. 9 15 I llME f3 1 1, 151 1 Z Tn 1; 2T+1 5 TH T+1 q TIME 0 g] A) n 2 16 1% I 2m, 8 T

X Scanningi cycle Y Scanning cycle Z, Scanning cycle D 56 inventor B Serge A. Scherbufskoy Patented Sept. 15, 1953 SYSTEM.AND APPARA ING THE LISTENIN TUS- FOR DETERMIN- G. HABITS OF WAVE SIGNAL RECEIVER USERS Sergev A. Scherbatskoy, Tulsa;

ielsen Company,

A. C. N ration of Illinois Okla; assignor to Chicago, Ill.,, a.corpo-- Applicationoctober 24, ll947', S'erialNo. 781,986

8- Claims.

1 lhe present invention relates to systems and apparatus for determining the listening habits. of users of. wave signal receivers of. the broadcast type, andmore particularly to improvements in systems and apparatus for determining the. audi ence popularity or rating of different programs transmittedlfrom' one or more wave signal transmitters and for gathering other information of great importance in determining. the effectiveness otradio .advertising.

Instrumented methods of determining the listening habits-.ofhomeradio receiver users. generally. involve the? use. of; arecording device operating. in. conjunction, with each collaborator receiverusedin: the samplingsystemto record the extent-of. use of. thereceiver andto. record as a function: ofa time, the. wave; signaltransmitters to which the receiver istuned for program reception. Theusual device 'ofrthis character embodies facilities for driving arecording. element such L as aatape for; example. ata constant speedand translating means for variablyv positioning a recording stylus 0r other-recording means-relative to a: recording, element in accordance with changes in .the :tuningof the wave signal receiver. The positions.- of the record indicationsaalongthe recording, element provide the necessary recordinginformation from'which it is possible to .determine the particular stations to. whichqthe receiver was tunedandalsoxthelength of timeto; which the various stations were. tuned in by. thereceiver. Thus-with agiven starting time of: the recording element accurately marked thereon each following point along therecording; element. is. representative of alater chronological instant: so long as.the recording. element is driven at a constant speed.

In general, two different typesof. recording devicehave been'used to produce arecord of the extent of receiver use and with the; angular setting. imparted to the con-- denser tuning-shaft. Whilethis type of deviceis entirely satisfactory in operation, it is not adapted for. usein conjunction with all makesand'types of broadcast-receivers. Thus,- the connection between-the recorder. stylus and the-receiver tuning the particular trans-- mitters to which the receiver is tunedxforprogram tions to which one shaft dictates the positioning of the recorder in thereceiver cabinet, which bars its use in conjunction with small receivers having limited unoccupiedcabinet space. The second type of recording-device-is electro-mechanical in that an electip-mechanical translating system is interposed between the'high frequency signal channel of the receiver and the station recording stylus to control the movement of the-stylus in-its operation to record on a time basis the particular transmitter from which programs are received. Prior art instruments of the second type are principally of the wavemeter construction wherein the local oscillator of the receiver is coupled to a sweeping wavemeter through a small coupling capacitor. This coupling capacitor-is located directly at the oscillator circuit of the receiver and a shielded or unshielded conductor is used to transmit the local oscillator output signal to the wavemeter. Due to signal attenuation over this conductive transmission channel; the coupling conductor must be relatively short, which means that the wavemeter and? recording instrument must be located within a-few feet of the receiver. Present instruments of the wavemeter type are rather bulky and'hence are difficult to conceal or make inconspicuous in the-average home. It is possible to. use a highly'sen'sitive wavemeter witha long coupling conductor, but there are objections to running: such a; conductor along the floors or walls oftheaverage home. Further, if the conductor is long, it definitely must be. shielded to prevent noise pick-up and to prevent undesired broadcasting of'thelocal oscillator output signal or" the receiver; Moreover, the use of a long couplingcable prevents movement of the receiver unless. a skilled installation: mani available to relocate the receiver; Thus, prior art instruments ofthesecond type-are bulkyanddifiicult tomake inconspicucuszand restrict mobility of the associated receiver. Moreover; one complete and independent instrument is required for: each receiver the use of which is to be monitored, thus requiring considerable duplication of equipment in.multi-radiosccllaborator homes.

It, i wan objector the present invention, therefore, to at least in partobviate theabove-mentioned disadvantages of prior art systems: and apparatus for recording the. transmitting staor more wave signal receivers are tuned.

It is another object of the present inventionto provide improved apparatus and. an. improved system of the character described .whichprovides for record monitoring of'a plurality of receivers 3 with a relatively small amount of apparatus, the majority of which may be located at any desired point distant from the receivers, which receivers may be of the multi-band type including amplitude modulation, frequency modulation and television channels.

It is another object of the present invention to provide a new and improved arrangment for use with any receiver of the superheterodyne type including simple and compact facilities which may easily be installed in a receiver cabinet for supplying to a remote recording point a signal having a variable characteristic uniquely representative of particular transmitting stations to which the receiver is tuned for program reception and furthermore to produce signals uniquely representative of a particular receiver where a plurality of receivers in a multiple receiver home are monitored.

Still another object of the present invention is to provide new and improved apparatus for producing information relative to the particular transmitting station to which a wave signal receiver is tuned, including means for scanning the frequency spectrum in a stepwise manner together with means for producing an indication of the particular transmitting station to which a receiver is tuned by the position of said transmitting station with reference to a series of discrete steps in said frequency spectrum.

It is another object of the present invention to provide an improved apparatus for recording the listening habits of wave signal receiver users in a readily decoda'ble manner.

It is a further object of the present invention to provide by means of a plurality of bursts of electrical energy an indication of the articular transmitting station to which a wave signal receiver is tuned, the number of bursts of energy occurring during each time interval such as each minute being representative of the particular transmitting station.

Further objects and advantages of the present invention will become apparent as the following description proceeds and the features of novelty which characterize the invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

For a better understanding of the present invention reference may be had to the accompanying drawings in which:

Fig. 1 is a schematic diagram of a multiple band radio receiver and associated apparatus for producing a signal uniquely representative of the particular transmitting station to which said receiver is tuned as well as uniquely representative of the particular receiver,

Fig. 2 is a schematic diagram of a recorder unit adapted to record information supplied by a plurality of units of the type shown in Fig. 1 which are associated with a plurality of receivers.

Fig. 3a is a graph of frequency vs. time indicating a plurality of discrete frequencies which 'might be employed in scanning the amplitude modulation frequency range.

Fig. 3b is a graph similar to Fig. 3:: showing the beat frequency impulses generated as a result of heterodyning the discrete frequencies of Fig. 3a with the signal from the local oscillator of a receiver when tuned to a particular broadcasting station.

Fig. 4 is a graph similar to Fig. 3a of the fre- 4 quency modulation and television frequency range.

Fig. 5 is a graph of periodically recurring characteristic beat impulses existing at the input to a rectifier or detector employed in the apparatus of Fig. 1 when the particular radio transmitting station considered in connection with Fig. 3b is tuned in by the wave signal receiver of Fig. 1.

Fig. 6 is a graph illustrating certain electrical characteristics of the apparatus of Fig. 1 when the wave signal receiver of Fig. 1 is tuned to the particular transmitting station considered in Figs. 3b and 5.

Fig. '7 is a graph similar to the graph of Fig. 6 but representative of certain conditions when a diiferent radio transmitting station is tuned in by the receiver of Fig. 1.

Fig. 8 is a graph illustrating the output of an oscillator associated with the apparatus of Fig. 1 when no biasing voltage is applied thereto.

Fig. 9 is a graph similar to Fig. 8 indicating the output of the oscillator when the wave signal receiver of Fig. 1 is tuned to the particular broadcasting station corresponding to the one considered in connection with the graphs of Figs. 5 and 6.

Fig. 10 is a graph similar to Fig. 9 but with the wave signal receiver of Fig. 1 tuned to the radio transmitting station corresponding to the one considered in connection with the graph of Fig. '7, and

Fig. 11 is an enlarged section of a recording element with representative records made thereon by the recording device of Fig. 2 when three separate receivers each employing an apparatus similar to that disclosed in Fig. 1 are monitored.

It should be understood that the present invention is particularly applicable to a system for monitoring the receivers in a multi-receiver home, in which case the apparatus of Fig. 1 would be duplicated in dependence upon the number of receivers in the home. The apparatus of Fig. 2 is illustrated as capable of recording the information from three separate receivers. It will be understood that the system and apparatus is capable of functioning where one or more receivers in a home are to be monitored and the apparatus is especially adaptable for use in multi-receiver homes.

The signal producing apparatus of Fig. l is illustrated as being applied to a wave signal receiver which is capable of receiving amplitude modulation signals, as well as frequency modulation signals including television signals. It will be understood that the invention is equally applicable to simple receivers operating in only a single frequency band in which case the apparatus would be considerably simplified. The more complete disclosure is included in order to show the more general application of the present invention.

. Referring now to Fig. 1 of the drawings there is disclosed and briefly described hereinafter a system for determining the listening habits of radio receiver users in order that the apparatus of the present invention associated therewith may better be understood. It is assumed that for a three-receiver home, three separate units such as shown in Fig. 1 which is illustrated together with the associated wave signal receiver, will be employed, each unit capable of transmitting three different signals representative of the particular wave signal receiver involved, to a recording unit such as is shown in Fig, 2 of the w ngs. The signal transmission between a unit such as is disclosed in Fig. 1 and the recording unit of Fig. 2 may be by space link or as illustrated by a suitable conductor link which may comprise the house wiring circiut of the particular home under consideration. The signals from three separate units of the type disclosed in Fig. 1 would preferably differ as far as identifying the wave signal receiver is concerned with respect only to the carrier frequency involved. As an example three separate units of the type illustrated in Fig. 1 may be capable of producing signals having carrier frequencies of 40, 50 and 60 kilocycles respectively. Since the units such as are disclosed in Fig. 1 would be identical for each receiver being monitored these units have not been duplicated in the drawings, but it should be understood that with the recording unit shown in Fig. 2, three units such as are illustrated in Fig. 1 would be employed.

The wave signal receiver illustrated by the reference numeral It in Fig. 1 forms no part of the present invention but is merely representative of a wave signal receiver which may be monitored by the apparatus and system of the present invention. As illustrated this wave signal receiver comprises an amplitude modulation section generally designated at H, a frequency modulation section generally designated at l2, an audio requency section generally designated at 3, and a television recording section generally designated at I4. It will be understood that the various sections of the receiver It are entirely conventional. The amplitude modulation section II preferably comprises an antenna ground circuit designated at E5, a tunable radio frequency amplifier IS, a mixer or modulator ll, an intermediate frequency amplifier l8, and a detector and automatic gain control unit is connected in tandem in the order named. The usual local or beat frequency oscillator is associated with L the mixer or modulator I 1, whereby the received program signal carrier is heterodyned to a fi e intermediate frequency.

The frequency modulation section l2 of the Wave signal receiver an antenna ground circuit 2| which ma be identical with the circuit indicated at It associated with amplitude modulation section of the receiver H). In addition to the antenna ground circuit 2| the frequency modulation section in- I cludes a tunable radio frequency amplifier 22, a modulator 23, an intermediate frequency ampliher 24 and a detector 25 connected in tandem in the order named. A local or beat frequency oscillator 26 is connected to the mixer or modulator 23 in the conventional manner. The outputs of the detector units I9 and 25 are each connected to an audio frequency amplifier 21 and thence to a speaker or signal reproducer 28 forming a part of the audio frequency section 13 of the receiver I 0'.

For the purpose of supplying filament current to the wave signal receiver H! as well as screen and anode potentials for the electron discharge tubes provided in the various stages of the receiver H) a suitable power supply unit specifically designated by the reference numeral 29 is provided which forms an integral part of the receiver Ill. This power supply unit 29 is adapted to be excited from the usual 110 volt alternating current source specifically designated at 34 over a power supply cord 35 which is connected to the source 34 through a conventional plug connector including the plug 36 and the socket 3.1. It will be understood that the power source 34 forms a p I!) is illustrated as comprising of the currentdistribution system for the dwellin in which the receiver III is located and these conductors extend to or are parallel connected with other conductors in different rooms of the dwelling.

In general the receiver In as described above is entirely conventional in arrangement and its mode of operation is well understood by those skilled in the art. Briefly, however, program modulated signal carriers intercepted by the antenna ground circuits l5 or 2| are selectively transmitted through the amplitude modulation or frequency modulation sections wherein they are selected and amplified by the tunable radio frequency amplifiers 16 or 22, converted into a modulated carrier of fixed frequency at the mixer or modulator stages I! or 23', further selected and amplified in the intermediate frequency amplifiers It or 24 and detected in the detector units l9 or 25. The program or modulation components developed in the units [9 or 25 are amplified by the audio-frequency amplifier 2! and delivered to the loud speaker or signal re-producer 28. In the event of television signals they are delivered from the unit 24 to the television apparatus 14 for reproduction. Automatic gain control of One or more of the receiver stages I6, I l and I8 under the control of the gain control bias developed in the unit I!) is accomplished-in an entirely conventional manner. Selection of different desired program modulated signal carriers originating at different transmitting stations is of course ac-: complished by adjustment of the tuning elements of the tunable radio frequency amplifiers I6 or 22 and to an even greater extent by adjustment of the tuning means such for example as the tuning condensers 20a and 26a of the local oscillators 20 and 26 respectively to vary the output frequency of these oscillators.

With superheterodyne receivers of the type illustrated by the reference numeral ID the reception of any program carrier from a given Wave signal transmitter Will be represented by a definite output frequency of the local oscillator of each receiver or the local oscillators of a receiver such as it having a plurality of signal channels. These output frequency signals of the local oscillators such as 20 and 26 may be used to identify the particular transmitting stations to which the receiver It is tuned for program rece tion at any particular time. In accordance with the present invention the output of the local oscillator 29 s supplied through a suitable coupling capacitor 3| to a unit which might be referred to as a transmitting unit or receiver attachment generally designated at 30, which unit forms an essential part of the present invention and is described in detail hereinafter. Similarly the output of the local oscillator 26 is connected through a suitable coupling capacitor 32 with the unit 38 to be described hereinafter. In either case the signals supplied through coupling capacitor 3| or 32 are representative of the particular radio transm tting station to which the wave signal receiver is tuned.

Although the apparatus disclosed and described in this application is preferably disposed in a single home of the single or multireceiver type it should be understood that in actual practice several hundred broadcast receivers located in homes within the radiation areas of different sets of wave signal transmitters which are broadcasting the particular programs. of interest are monitored to provide the record information concerning the listening habits of the receiver users necessary' to a statistical analysis from which the various factors affecting the sales effectiveness of particular programs may be accurately arrived at. In using the system it is contemplated that selection of the system collaborator homes-that is the homes in which wave signal receiver use is to be logged-shall be on a basis such that all of the variable factors, such for example, as the number of potential listeners, economic afliuence, religion, etc., which normally affect any process of sampling public opinion are accounted for on a weighted basis. In the interests of simplifying the disclosure, however, the transmitter and recording units for only a single multi-receiver home are shown in Figs. 1 and 2 of the drawings.

In accordance with the present invention the transmitting unit 30 is capable of converting the signal frequencies from the local oscillators 20 and 26 to indications uniquely identifying the particular transmitting station to which the wave signal receiver I is tuned which indications are readily capable of being recorded so that a record may be obtained of the tuning condition of the wave signal receiver with respect to time. Furthermore the recordings are such as to be readily decoded. In order that a plurality of wave signal receivers such as I!) may be monitored in a multireceiver home the transmitter unit 30 should also be capable of producing indications uniquely identifying the receiver l0 as well as the transmitting stations to which the wave signal receiver I0 is tuned.

Accordingly the transmitter unit 38 is provided with means for continually scanning the frequency spectrum within the range of the frequencies of the local oscillators and 26. In order to simplify the construction and still provide an arrangement for scanning the whole frequency spectrum including the amplitude modulation, frequency bands, the transmitter unit is provided with a stepwise scanning arrangement wherein the frequency spectrum is scanned in a finite number of steps, each step corresponding to a receivable transmitting station. It will be understood that in any particular locality the number of transmitting stations to which a receiver is generally tuned is fairly limited. One factor which limits the number of transmitting stations is of course the relative ranges of the receiver and transmitting stations. In addition the advantageous reception obtainable from a finite number of stations over the reception of other stations which might be tuned in but whose transmitting characteristics are not too favorable for good program reception mitigates against tuning the receiver to more than a limited number of transmitters. When it is desired to scan the entire frequency spectrum with a multiple band wave signal receiver such as I0, band switching is generally required in any event so that the employment of a stepwise switching arrangement does not in- ,volve much added apparatus.

In accordance with the present invention the transmitter unit 30 embodies the principle whereby each of a finite number of frequency channels is given an arbitrary index which has no simple relationship to its frequency and this index is recorded thereby giving an accurate indication of the transmitting station tuned in by the receiver It) at any particular time. Such an arrangement enables the employment of a plurality of fixed circuit parameters, which involves a simple design problem from the standpoint of .accuracy and stability as compared with the modulation, and the television difficult design problems involved where continually variable parameters are employed. As will be brought out hereinafter a signal representative of the station index may be produced by utilizing the same switch mechanism which is used in switching from channel to channel thus considerably simplifying the mechanism. The apparatus associated with the receiver H) can be of relatively small bulk as will become apparent particularly where the wave signal receiver involves only a single band.

The transmitter unit 30 of the present invention is essentially a small relatively insensitive receiver which could be of any type but which is specifically illustrated as of the superheterodyne type. In view of the dual band receiver It) being monitored, the receiver in the transmitter unit 30 is also a dual band receiver and comprises two oscillator modulator units or converters 40 and 4| respectively, each including a pcntagrid converter 42 and 13 respectively. The receiver in the transmitter unit 30 furthermore includes band pass filters 44 and 45 to which the outputs of the units 40 and 4| respectively are connected. The signals passed by the band pass filters M and 45 are in turn supplied to a detector or rectifier unit i6 which is provided with two discharge paths 45a and 461) respectively whereby the signals transmitted by both band pass filters 44 and 15 are detected.

Referred now specifically to the modulator unit 40 of the transmitter unit 30, it may be observed that the pentagrid converter 42 includes an anode 63, a cathode 6G, a first control grid 5!, a second control grid G8, a suppressor grid 65 and screen grids t6 and 61. The second control grid E8 is connected to the coupling capacitor 32 so as to receive the signal from local oscillator 26. In order to provide a path to ground for direct current a suitable radio frequency choke coil 49 is connected to the grid 48, which choke coil is grounded as indicated at 50. The first control grid 5| is connected to the tank circuit of an oscillator unit through a suitable coupling capacitor 52. The tank circuit includes an inductance 53 successively adapted to be connected in parallel with each of a lurality of capacitors 54, 55, 56 and 51. One common terminal of each of the capacitors 54 and 5! inclusive is connected to one terminal of inductance 53 of the tank circuit while the other terminals of the capacitors are connected to the switch contacts 54a, 55a, 56a, and 57a respectively which are adapted to be engaged by a movable contact or wiper 58 which in turn is connected to the other terminal of the inductance 53 of the tank circuit. The switch contacts 54a to 57a. inclusive are uniformly spaced in an arcuate manner so as to be successively contacted by the switch arm 58 upon rotation thereof. In addition to these contacts which have been mentioned an additional contact 59 is provided which is spaced from the contact 5M by substantially the same amount as the spacing between the other contacts and furthermore is adapted to be engaged by the wiper 59. The contacts 54a to 51a and 59 substantially define a semi-circle with the contacts peripherally arranged to provide with the wiper 58 a rotary switch mechanism.

For the purpose of rotating the switch arm 58 at a uniform speed to roduce a switching operation relative to the contacts 54a, 55a, 56a, 51a and 9 chronous motor is energized from any source of power designated at 62 and preferably is arranged to drive the arm 58 at a speed of one revolution per minute in a clockwise direction as viewed in Fig. 1.

The cathode B4 of the pentagrid converter 42, for feed back purposes, is connected to an intermediate point on the inductance 53 of the tank circuit. A suitable grid leak resistor 68 is connected between the control grid 5| and ground 50. It will be understood that rotation of the contact arm or wiper 58 will cause the frequency of the oscillator associated with the oscillator modulator unit 40 to vary in a stepwise manner so that a stepwise varying beat frequency will be obtained in the plate circuit of the electron discharge valve 42 by virtue of heterodyning the signal frequency of the local oscillator 26 with the output of the oscillator section of the converter 40. The plate circuit of the oscillator modulator unit 40 is connected to a source II! of +13 potential through a resistor II and a tuned circuit 72 comprising an inductance I3 and a capacitor 14. The screen grids 66 and $7 arranged in parallel are also connected to the source 1!] of +B potential, through a voltage dropping resistor 15. A suitable high frequency by pass condenser 16 is connected between the screen grids 66 and 61 and ground which is indicated at 11.

It will be apparent that the tuned circuit 72 forms a partof the band pass filter 44 which further includes a turned circuit I8- including the capacitor I9 and the inductance 89, which inductance is coupled with the inductance 13. As

will be better understood in the light of the ensuing description, preferably the band pass filter 44 is designed so as only to pass signals of a predetermined frequency and by way of example only frequencies of the order of one megacycle. The output of this band pass filter 44 is connected through a suitable conductor 8| with the cathode 82a of the discharge path 46a of the rectifier 46. i The oscillator modulator unit or converter 4| of the transmitter unit 30 is substantially identical with that of the unit 40 described above. The pentagrid converter 43 comprises an anode 4, a cathode 85, a first control grid 8-5, a second control grid 87, a suppressor grid 88 and a pair of parallel connected screen grids 89 and 'i'ifi. second control grid 87 is connected to the coupling capacitor 3! so as to receive signals from the local oscillator 26 of the wave signal receiver IB. These signals will be of the order of 1,000 to 2,000 kilocycles in frequency for the standard broadcast band of 550 to 1550 kilocycles. The first control grid 86 is connected to the tank circuit of an associated oscillator unit, through a coupling capacitor 0|. The tank circuit comprises the inductance 92 and one of a plurality of capacitors 93, 94, 95, 95, and 91 which are arranged to be successively connected in the tank circuit. Each of these capacitors 93 to 91 inclusive has one terminal thereof connected to one terminal of the inductance 92. The other terminals of the capacitors 93 to 91 inclusive are connected to contacts 93a, 94a, 95a, 96a, and El a respectively, peripherally arranged in spaced relationship so as to form with a movable arm or wiper 98 a rotary switch mechanism. The movable arm 9t is rotatable about an axis to successively engage the contact members 93a, 94a, 95a, 96a, and 91a in that order during one cycle of rotation thereof. The movable switch arm 98 is connected to the other terminal of the inductance 92 which con- The channels for very large receivers.

10' nection is grounded as indicated at .99. The cathode is connected to an intermediate point on the inductance 92 to produce the desired feed back. A suitable radio frequency choke coil me is connected between ground 99 and the second 1 equally spaced time intervals during one revolution which amounts to one scanning cycle. This can be accomplished as illustrated by having the wipers 58 and 98 fastened to the driving shaft so as always to be in the same angular position, and the contacts 93a, 94a, 95a, 96a, 91a, 54a, 55a, 56a," and arranged so as to be successively engaged in that order by one or the other of the wipers 58 and 98.

The plate circuit of the pentagrid converter 43 includes the tuned circuit I03 comprising the inductance IE9 and the capacitor I05. The source It of +3 potential is connected to the anode 84 through the resistor II and the tuned circuit IdS. The tuned circuit I03 comprises a portion of the band pass filter which includes an additional tuned circuit I06 comprising the capacitor I01 and the inductance I08 inductively coupled with the inductance I 03. The band pass filter 45 is also designed so as only to pass signals of a predetermined frequency and by way of example only frequencies of the order of 100 kilocycles. The output of the band pass filter 45 is connected to the cathode 62b of the discharge path 451) of the detector or rectifier 46.

In order to provide a cyclic control potential indicative of the transmitting station to which the wave signal receiver I0 is tuned the rectified potential obtained through operation of the detector or rectifier 45 is supplied to a capacitor IIEI through a current limiting resistor III. The capacitor I I0 is connected to ground as indicated at I I2. When a potential is applied to the detector 48 it will be apparent that the condenser I I0 is charged. The ungrounded terminal of the condenser H6 is connected by means of a conductor I I3 with the terminal 59 of the switching unit comprising the rotatable arm 58. Whenever the switch arm 58 engages the contact 59, which might be considered a reference terminal, the

condenser Ilt is provided with a discharge path to ground through the conductor H3, the switch arm 58, and the inductance 53.

Although the stepwise switching means comprising the rotatable arms 50 and 98 have been described as including only nine switch points representative of nine transmitting stations it will be apparent that this could readily be multiplied so as to scan eighteen or twenty-seven The number of channels is immaterial as far as the present invention is concerned and the nine channel unit is illustrated by way of example only. With a nine channel unit as illustrated it is possible to obtain information regarding five amplitude modulation transmitting stations having frequencies F'1, Fz, F's, F4 and F's as Well as four frequency modulation and television channels having frequencies F's, F'v, F's and F's respectively. By way of example such transmitting stations might be identified in accordance with Table III the following table.

Table I Corre- Idcntifying Search sponding 5 or Index Frequency Tuning Corresponding Station ggfg ygg g Frequency Corresponding to Station Number N 32;

F1=660 kc Broadcast Station WEAF. f1=l,215 kc. 93 Broadcast Station WEAF. F2=720 kc B oa cas Station j.=1,21s kc. 94 Broadcast Station WO n. F3=770 kc Br adcast tat o 13:1,325 kc 95 Broadcast Station WJZ. F4=880 kc Br adcast tat WABC- f4=l,435 kc. 9e Broadcast Station WABC. s= kc r Broadcast Station Q f5=2,l05 kc. 97 Broadcast Station WQX R. F@=45.5 mo M Station WFGG- f=51.0 inc. 54 FM Station wroo. 1=47.5 me"..- FM p t WABF- 11:53.0 rnc- 55 FM Station WABF. 'a= Inc-m Televlslon Channel 3 fa=66.75 mo. 56 Television Channel No. 3

(sound). F'o=83.25 mc. Television Channel No. 6 ,=gg mm Television Channel No 6 (sound). (sound).

If the intermediate frequency of the unit I! is 455 kilocycles and the intermediate frequency of the unit 24 is 4.5 megacycles, then Table I might be expressed in the following manner.

Table II Output Fre- Identifyin or e quency of Local Corresponding to Station Index Number N Oscillators or 26 1 F1=l,ll5 kc Broadcast station WEAF.

F:=l,175 kc.. Broadcast station WOR. Fa=1,225 kc... Broadcast station WJZ.

F4=L335 kc Broadcast station WABC. F5=2,005 kc.. Broadcast station WQXR. F8=50 Inc FM Station WFGG. F1=52 Inc FM Station WABF.

8.- FE=65.75 mc. Television Channel No. 3

(sound). 9 Fv=87.75 H10. Television Channel No. 6

(sound).

In accordance with the present invention the oscillator sections of the modulator units and 4| are capable of producing frequencies which will be designated hereinafter as search frequencies. In tuning the converter M in a stepwise manner the frequencies f1, f2, f3, f4, and is are produced in response to the insertion of the capacitors 93, 94, 95, 96 and 91 respectively into tank circuit through rotation of the wiper or switch arm 98. These and is are designated as the amplitude modulation search frequencies. Similarly the oscillator circuit of the converter 40 is tuned in stepwise manner to successively produce the discrete frequencies f6, f7, fs, and f9, upon the insertion of the capacitors 54, 55, 56 and 51 respectively into the tank circuit of the converter or modulator unit 40. These frequencies f6, f1, f8, and is are designated as the frequency modulation and television search frequencies.

In view of the fact that the band pass filter has been designated as passing only signal frequencies of the order of 100 kilocycles and the band pass filter 44 has been indicated as capable of passing only signal frequencies of the order of one megacycle, the search frequencies f f2, f3, f4, and it, are chosen so as to differ by 100 kilocycles from the frequencies F1, F2, F2, F4, and F5 respectively of the oscillator 20 when tuned to stations 1, 2, 3, 4 and 5 respectively as set forth in Tables I and II. Likewise the search frequencies is, It, ft, and is, for the frequency modulation and television channels are chosen so as to differ by one megacycle from the frequencies F6, F7, F8, and F9 respectively produced by the oscillator 26 when tuned to stations 6, '7, 8, and 9 respectively. Accordingly, in the fol lowing table are set forth the particular search frequencies which would be employed in the examples set forth above.

frequencies f1, f2, f3, f4,

It is apparent that if the synchronous motor 60 rotates the wipers or switch arms 58 and 98 at a speed of one revolution per minute and the contacts engaged thereby are uniformly spaced that the search frequencies f1, f2, f3, f4, f5, fa, f1, f8, and f9 will be produced in stepwise fashion, the frequencies f1, f2, f3, f4 and is, being produced in the converter 4| and the frequencies f6, ft, is and is, being produced in the converter 49. Assume for example that the wipers 58 and '98 are initially in the position indicated in Fig. 1 of the drawings with the wiper 58 engaging the reference contact 59. This time might be arbitrarily designated at time to. As the scanning progresses the wiper 98 contacts successively the terminals 93a, 94a, a, 96a and 91a at corresponding instants t1, t2, t3, t4 and 155. During this interval of time the wiper 58 leaves the reference terminal or contact 59 and moves through space until the wiper 98 leaves the contact terminal 91a, whereupon the wiper 58 successively engages the contacts 54a, 55a, 56a, 51a and 59 at the corresponding instants t6, t1, ta, t9, and T +to, where T is the period of one scanning cycle. The reference terminal 59 is periodically contacted at the beginning of each scanning period. Due to the uniform distribution of the contacts 93a, 94a, 95a, 96a, 91a, 54a, 55a, 56a, 51a and 59 and furthermore because of the uniform angular motion of the wipers 58 and 98, the instants to, t1, t2, t3, t4, is, is, iv, is, to, and T+to etc., succeed each other by equal time intervals. The occurrence of the search frequency impulses with reference to time are diagrammatically illustrated in Figs. 3a and 4. Two complete cycles are shown in Fig. 3a of the search frequency impulses f1, f2, f3, f4, and f5 and similarly two complete cycles of the search frequency impulses f6, f7, fa, and is, are shown in Fig. 4. The frequency scale in Fig. 4 is in megacycles while the frequency scale in Fig. 3a, is in kilocycles.

Assume for example that a particular broadcasting station such as station No. 2 in Table I is tuned in by wave signal receiver ID. This station has a transmitting frequency of Fz kilocycles and the local oscillator 20 supplies a frequency of F2 to th control grid 81 of the converter tube 43. It will be apparent that under these conditions a beat frequency will be produced by the heterodyne action which beat frequency will vary successively with the search frequencies, as the search frequency impulses f1, I2, f3, f4, and f5 are produced the beat frequencies of (f1F2), (,fzF2), (fsF2), (f r-F2) and (f5-Fz) are successively produced. These beat frequencies are indicated in Fig. 3a and the time of occurrence thereof for two cycles or two periods is specifically designated in Fig. 3b of the drawings. During the portion of the scanning cycle when the search frequencies f6, 7%, :fs, and is are produced when the wave signal receiver I is tuned to the transmitter whose frequency is Fz no beat frequency impulses are produced .because local oscillator 2B is not connected to the converter 40. In view of the fact that the band pass filters 44 and 45 will only pass signal frequencies of one megacycl and 100 kilocycles re spectively, only the frequency occurring at the instant t2, (T-l-Zz), (2T+tz),-etc., will be passed by the band pass filter 45 since only at those instants is the beat frequency output of the converter unit 4| equal to 100 kilocycles. Fig. 5 represents the impulses applied to the-rectifier or detector unit 46 for three scanning cycles when the station having a transmitting frequency Fz is tuned in by the-Wave signalreceiver IEI. It will be understood that if any other transmitting-station is tuned in by the Wave signal receiver I0 impulses coresponding to those in Fig. 5 .will be applied to the rectifier 46, which impulses will occur at the instants (tzv), (T-l-tzv), (2T+t-), etc., where N is the index number of the particular transmitting station to which the wave signal receiver is tuned. It will be apparent therefore that there has been provided an ar rangement whereby an indication of the partic ular transmitting station is obtained in dependence upon its arbitrary position in a stepwise scanning cycle.

For the purpose of producing readily recordable indications which are capable of uniquely identifying the receiver Ill as well as the particular transmitting station to which the receiver maybe tuned there is provided in accordance with the present invention an oscillator including the electron discharge tube IIE which comprises an anode H5, a cathode I I l and a pair of control electrodes or grids H8 and H9. This oscillator also includes a winding IBM and a capacitor IZUb arranged in a tank circuit (I2?! which is connected to the control electrode IIB whereby the oscillator is caused to produce an output having a frequency of a predetermined constant value such as 60 kilocycles for example. The plate circuit of the electron discharge tube I I5 which includes a suitable winding I 2 i, aconductor H4, a switch I22, and a current limiting resistor I23 is connected to a source I24 of +13 potential. The cathode II'l of the tube M5 is grounded as indicated. If the switch I22 remains closed, an oscillator output having a frequency determined by the tank circuit I 2-5! such as 60 kilocycles or th like is produced in the winding I2I which is preferably inductably coupled with a winding E25 suitably connected to the house wiring circuit 34 as by a plug connector comprising the members I26 and I27. Acapacitor its is preferably provided in this circuit to prevent the transfer of currents having frequencies substantially below the 60 kilocycle frequency produced by the oscillator including the tube H5. The windings I2Ila, I 2! and I25 essentially act a three-winding transformer. A. si-iitable resistor I39 is provided to control the application of the proper potential to the grid I I 8.

In accordance with the present invention the switch I22 is cyclically operated as by means of a rotatable cam I3! which is driven by the chronous motor 80. Preferably cam Iiil is provided with ten protrusions equally spacedand ar ranged so as to cause the switch I22 to close each time that the wipers 53 or 98 engage one of their associated contacts. In other words the cam I3 I 14 causes switch .122 to close at the instants to, 151,12, t3, t4, is, is, t7, is, is, T-I-to, T-I-ii, etc. With this arrangement:it:isapparent-that without the provision of control electrode .I-I9, the oscillator including the tube I15 will produce bursts or impulses of '60 kilocycle energy at the instants to, h, tz, etc., as :indicated'by Fig-8 of the drawings.

.In accordance with thepresent invention the capacitor H0 is connected to the control electrode H9 in a manner such that when capacitor III] is charged the voltage applied to control electrode H9 renders oscillator tub H5 non operative. Considering as an example the condition when the station having'a transmitting frequency of F'z is tuned in bythe wave signal receiver I0, it will be apparent from an examination of the curves of Fig. 5 that a voltage will be applied to the capacitor III? at the instants t2 during every scanning cycle :and the capacitor IIO remains charged from th time t2 until the time T-I-to etc., when the capacitor I I Q is discharged by engagement of the wiper 58 with the reference terminal 59. By virtue of the resistance I II a small interval of time At expires before the capacitor IIB is charged. Fig. 6 illustrates the voltage-conditions of the capacitor H8 for the condition when the wave signal receiver Iii is tuned to the transmittingstation having a transmitting frequency of Fz and an index number of N :2, the shaded areas indicating the periods when the condenser IIii is charged. When the wave signal receiver I G is tuned to the transmitting station having the frequency .F'v the cyclic voltage condition of the condenser or capacitor I-llii is represented by Fig. 7 of the drawings with the shaded areas again indicating the charged periods of the condenser. It will be apparent that depending upon the particular station whichis tuned inby the Wave signal receiver Ill, the capacitor I It! will be charged for variable periods of time during each scanning cycle and will be discharged at the end of each scanning cycle by the engagement of the wiper 53 with the reference terminal 59.

In View of the fact that control electrode H9 is connected to the ungrounded terminal of the capacitor III] the voltage of the capacitor II B will also be the voltage of the control electrode H9. Consequently when the station having a. transmitting frequency of F'z is tuned in by the Wave signal receiver I0 the oscillator H5 is capable of producing bursts of GO-kilocycle energy only at the instants of ti and t2 during everycycle as .is shown by Fig. 9 of the drawings. Similarly when the transmitting station having a frequency of F"; is tuned in by the wave signal receiver I0 the oscillator tube H5 is capable of producing bursts of 60 kilocycle energy whenever the switch 122 is closed and no voltage exists on the capacitor :II I). This is indicated by the curve of Fig. 10 of the drawings. It will be apparent therefore that with the arrangement described N bursts of 60 'kilocycle energy will be produced during each cycle where N is the index number of the particular station tuned in by the wave signal receiver ID. If more than one wave signal receiver were provided in a particular home as many transmitter units such as 36 as there are receivers would be provided, one associated with each receiver, and each would have oscillators such as II 5 capable of producing bursts of energy of different frequencies but in each case the number of bursts of energy during any scanning cycle would correspond with the index number of the 15 particular station tuned in by the wave signal receiver.

It will be understood that with the transmitter unit 3|] of the present invention any suitable recording device may be employed which is preferably disposed in an out-of-the-way place such as a closet or the basement of the home in which the receiver users whose listening habits are be ing considered live. Such a recorder is illustrated in Fig. 2 of the drawings, where the house wiring circuit is designated by the same reference numerals as in Fig. 1. This recorder unit is designated by the reference numeral I50 and comprises a plurality of channels designated as channel A, channel B, and channel C respectively, so as to record information produced by a plurality of transmitter units such as 30. As illustrated the channels A, B and C are connected to the signal link which is illustrated as the house wiring circuit 34 through a suitable plug connector designated at I5I. Each of the channels is identical and the corresponding parts are designated by the same reference numerals marked with an appropriate subscript such as a, b and respectively. The channel A simply comprises a band pass filter I52a, an amplifier [53a and a rectifier I54a connected in cascade in theorder named. The band pass filters I52a, I52!) and I52c are arranged so as to pass frequencies which differ from each other so that it is possible to identify the particular wave signal receiver. The frequencies of the band pass filters correspond with the frequency of the oscillator tube II of the associated transmitter unit such as 36. As

illustrated in Fig. 2 the band pass filter I52a is I.

designed to pass only frequencies of 60 kilocycles while the band pass filter I521) will passonly frequencies of 50 kilocycles and the band passfilter I520 will pass only frequencies of kilocycles. In any event the signals transmitted by the common link 34 can only pass through the particular channel which corresponds to that of a particular wave signal receiver being monitored.

As illustrated in Fig. 2 of the drawings the recorder also comprises a movable recording element I56 which may be any well known type of recording element such as magnetic wire or tape or as illustrated, a record tape having perforations along the edge thereof so as to be drivingly engaged by driving sprocket I51 connected to a suitable driving motor I56 through a shaft I59. The tape is preferably supplied to the sprocket I51 from a suitable supply spool I66 and the exposed tape is wound up on a suitable take up spool I6I. In general it is common practice to drive the movable recording element I56 at a constant speed, so that the amount of tape used in a predetermined time interval is indicative of the elapsed time. Preferably therefore the driving motor I58 is a synchronous motor which is illustrative as being connected to the house wiring circuit 34 which is preferably a 60-cycle 110 volt circuit.

Preferably the recorder I59 is of the type ca pable of making a phonographically reproducible record and is illustrated as of the type disclosed in prior copending Scherbatskoy application (N5) Serial No. 709,017 filed November 9, 1946 and assigned to the same assignee as the present application. In this preferred embodiment the movable recording element I56 comprises cellophane tape. For the purpose of producing high fidelity recording on the cellophane tape I56 a plurality of jewel tipped cutting styli I62, I63

5 ning cycle is of one minute and I64 respectively are provided, associated with the channels A, B and C respectively. These jewel tipped cutting styli I62, I63 and I64 are each preferably pivotally supported as a part of an associated recording head such as IBM, I63a and I64a respectively. When a signal is transmitted through channel A the stylus I62 will be caused to move in accordance with the signal to cut a trace in the cellophane tape I56. It will be understood that this signal will be representative of the bursts of energy produced by the oscillator tube II5. The operation of the other styli I63 and I64 will be identical.

For the piu'pose of better understanding the type of record produced reference may be had to Fig. 11 of the drawings where the traces I12, I13 and I14 produced by the styli I62, I63 and I64 respectively are shown in greatly magnified form at least as far as the lengthwise scale of the tape I56 is concerned. As illustrated the portion of the tape I56 shown in Fig. 11 contains records produced during three complete scanning cycles which are specifically designated as the X, Y, and Z scanning cycles. If each scanduration the magnified record of Fig. 11 is substantially that recorded during a three-minute interval. An examination of the trace I12 indicates that the particular wave signal receiver associated therewith was tuned to the transmitting station having an index number of N :2 during the X scanning cycle since two impulses are recorded indicating that the associated oscillator tube H5 produced two bursts of energy during this cycle. During scanning cycles Y and Z, however, it is noted that ten impulses are recorded during each cycle indicating that the cam I3I was causing the associated oscillator M5 to produce ten bursts of energy during each scanning cycle. It will be apparent therefore that during the scanning cycles Y and Z the wave signal receiver associated with the stylus I62 producing the trace I12 is turned on but is not tuned to any one of the stations for which a corresponding search signal is produced by the transmitter unit 30. In effect, therefore, the portion of trace I12 designated as I12a indicates tuning to all other stations which means all stations other than those for which a particular search frequency is provided. The recording of such information is fairly important since if the record produced on the movable element I56 indicates that the receivers being monitored are tuned for substantial periods of time to all other stations then it may be desirable to produce additional search frequencies during each scanning cycle.

An examination of the trace I13 in Fig. 11 indicates that the particular wave signal receiver associated with the stylus I63 is continuously tuned during all the scanning cycles shown to the transmitter having the index number N=7. An examination of the trace I14 indicates that during scanning cycles X and Y the particular Wave signal receiver associated with the stylus I64 is turned off, but that during the succeeding scanning cycles for which a trace is indicated in Fig. 11 the associated receiver is turned on and tuned to the station having the index number N :1.

The production of a record such as is disclosed in Fig. ll. lends itself very well to decoding. The exposed record tape may be run through a frequency meter or cycle counter which counts the cycles or pulses occurring during each scanning cycle thus permitting ready conversion of the number of impulsesper scanning cycle to trans.-

mitting station tuned in. It will be understood that the number of receivers being monitored is substantially unlimited as far as a particular recorder l 50 is concerned.

The terms phonographic reproducer and pho-. nographically reproducible as used herein denote any system or method of translating the record indications into electrical signals by phonographic pick up means and excludes visual scan-. ning and photographic duplicating processes. Under this definition magnetic records on amagnetic tape or wire may be considered the full equivalent of the cellophane tape system described above.

In view of the detailed description included above, the operation of the system and apparatus of the present invention will be apparent to those skilled in the art. When a particular transmitting station is tuned in by one of the wave signal receivers such as In the associated transmitter unit 30 produces bursts of electrical energy of a predetermined frequency indicative of a particular receiver and the number of bursts during each minute is a clear indication of the transmit-.- ting station tuned in. When a transmitting station having a frequency of transmission of Fz is tuned in the bursts of energy applied to the link 34 and consequently to the recorder I50 are represented by Fig. 9 of the drawings. transmitting station having a broadcasting frequency of Fq is tuned in by one of the wave signal receivers such as H) the associated transmits ter unit such as 30 will cause seven impulses to be applied to the associated stylus of the recording device I50 during each cycle. Generally speaking, therefore, when a radio transmitting station having a broadcasting frequency of FN is tuned in, N bursts of energy Will be produced by the transmitter unit and supplied to the recording element 159 through the link such as 34 Where N is the index number of the particular transmitting station.

It will be apparent to those skilled in the art that the present invention is not limited to the particular constructions and arrangements shown and described, but that changes and modifications can be made without departing from the spirit and scope of the invention, and it is aimed in the appended claims to cover all such changes and. modifications.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. Apparatus for recording information relative to the particular transmitting station to which a wave signal receiver is tuned comprising, means for continually scanning the frequency spectrum by producing a signal varying in frequency in a series of discrete steps during each scanning cycle each frequency step representative of a particular transmitting station, means for producing during each scanning cycle a plurality of periodic signals equal in number to the number of scanning steps, and means responsive to the production of the predetermined one of said frequency steps representative of the transmitting station to which said receiver is tuned for rendering said last mentioned means ineffective for the portion of each scanning cycle remaining after the production of said frequency step, the portion varying in dependence upon the particular transmitting station to which said wave signal receiver is tuned.

2. Apparatus for recording information relative to the particular transmitting station to When a which a wave signal receiver :is tuned comprising means for continually scanning the frequency spectrum by producing a signal varying in frequency in .a series ofdiscrete steps during each scanning cycle each frequency step bearing a predetermined frequency relationship with the frequency of transmission of a different transmitting station, means for producing during each scanning cycle a plurality of periodic pulses uniformly displaced with reference to time, and means responsive to the production of the predetermined one of said frequency steps representative of the transmitting station to which said receiver is tuned for rendering said last mentioned means ineffective for the portion of each scanning cycle remaining after the production of said. frequency step the portion varying in dependence upon the'particular transmitting station to which said wave signal receiver is tuned.

3. Apparatus for producing information relative to the particular transmitting station to which a wave signal receiver is tuned comprising means for continually scanning the frequency spectrum by producing a signal varying in frequency in a series of discrete steps during each scanning cycle each frequency step bearing a predetermined frequency relationship with the transmitting frequency of a different transmitting station, means for producing during each scanning cycle a plurality of bursts of electrical energy of a predetermined frequency which frequency is uniquely representative of said receiver, the number of bursts capable of being produced being at least equal to the number of scanning steps, and means responsive to the production of the predetermined one of said. frequency steps representative of the transmitting station to which said receiver is tuned for rendering said last mentioned means ineffective for portions of each scanning cycle so that the number of said bursts occurring during each scanning cycle is representative of the particular transmitting station to which said receiver is tuned.

4; In a system for producing for record purposes information relative to the particular radio transmitting stations to which a wave signal receiver is tuned, an oscillator, means including step switching means for causing said oscillator to produce an output having a plurality of discrete frequencies each of which is related to the transmitting frequency ofa different one of said radio transmitting. stations, each discrete frequency differing from its related transmitting frequency by a predetermined.frequency, means for heterodyning a signal obtained from the local oscillator of said wave signal receiver with the output of said oscillator, means for. operating said means including said: step switching means to cause an output of said discrete frequencies to be produced successively during each cycle of operation and in constantly recurrin cycles, whereby a beat frequency signal of a frequency equal to said predetermined frequenc is periodically produced at the instant during each cycle when the output of said oscillator is of the frequency which differs from the frequency ofv the signal being received by said wave signal receiver by said predetermined frequency, a second oscillator for producing an output of a predetermined frequency, means for periodically interrupting the plate circuit of said oscillator so as tocause it to produce periodic pulses of energy uniformly spaced with reference to time which spacing corresponds to the spacing between the steps of said step switching means, and means responsive to the receipt of said beat lator ineffective to produce said periodic pulses during the remainder of said cycle whereby the number of pulses produced during each cycle is representative of the particular transmitting station to which said wave signal receiver is tuned.

5. In a system for producing for record purposes information relative to the particular radio transmitting stations to which a wave signal receiver is tuned, an oscillator, means including step switching means for causing said oscillator to produce an output having a plurality of discrete frequencies each of which is related to the transmitting frequency of a different one of said radio transmitting stations, each discrete frequency differing from its related transmitting frequency by a predetermined frequency, means for heterodyning a signal obtained from the local oscillator of said wave signal receiver with the output of said oscillator, means for operating said means including said step switching means to cause said discrete frequencies to be produced successively during each cycle of operation and in constantly recurring cycles, whereby a beat frequency signal of a frequency equal to said predetermined. frequency is periodically produced at the instant during each cycle when the output of said oscillator is of the frequency which differs from the frequency of the signal being received by said wave signal receiver by said predetermined frequency, means for producing periodic pulses of energy uniformly spaced with reference to time which spacing corresponds to the spacing between the steps of said step switching means, and means responsive to the receipt of said beat frequency signal of said predetermined frequency during each cycle for preventing said last mentioned means from producing said periodic pulses during the remainder of said cycle whereby the number of pulses produced during each cycle is repre= sentative of the particular transmitting station to which said wave signal receiver is tuned.

6. Apparatus for producing information relative to the particular transmitting station to which a wave signal receiver is tuned, comprising, means for continually scanning the frequency spectrum by producing a signal. varying in frequency in a series of discrete steps during each scanning cycle each frequency step being repre sentative of a particular transmitting station capable of being tuned in by said receiver, means responsive to the production of the predetermined one of said frequency stens representative of the transmitting station to which said receiver is tuned for producing a predetermined electrical impulse during each scanning cycle the position of which in said cycle is representative of a particular transmitting station tuned in by said reoeiver, a control device operative in a predetermined manner during each cycle, means for changing the operation of said control device in response to the receipt of said predetermined electrical impulse, and automatic means operative at the end of each cycle for restoring said control device to its initial operating condition.

'7. Apparatus for producing information relative to the particular transmitting station to which a wave signal receiver is tuned, comprising, means for scanning the frequency spectrum by producing a signal varying in frequency in a series of discrete steps during each scanning cycle each frequency step being representative of a particular transmitting station capable of being tuned in by said receiver, means responsive to the production of the predetermined one of said frequency steps representative of the transmitting station to which said receiver is tuned for producing a predetermined electrical impulse during each scanning cycle the position of which in said cycle is representative of a particular transmitting station tuned in by said receiver, a control device operative in a predetermined manner during each cycle, means for rendering ineffective the operation of said control device in response to the receipt of said predetermined electrical impulse, and automatic means operative at the end of each cycle for restoring said control device to its initial operating condition.

8. In a system for producing for record pur poses information relative to the particular radio transmitting stations to which a wave signal receiver is tuned, an oscillator, means including step switching means for causing said oscillator to produce an output having a plurality of discrete frequencies each of which is related to the transmitting frequency of a different one of said radio transmitting stations, each discrete frequency differing from its related transmitting frequency by a predetermined frequency, means for heterodyning a signal obtained from the local oscillator of said wave signal receiver with the output of said oscillator, means for operating said means including said step switchin means to cause an output of said discrete frequencies to be produced successively during each cycle of operation and in constantly recurring cycles, whereby a beat frequency signal of a frequency equal to said predetermined frequency is periodically produced at the instant during each cycle Wllu'fl the output of said oscillator is of the frequency whi'h differs from the frequency of the signal being received by said wave signal receiver by said predetermined frequency, a second oscillator for producing an output of a predetermined frequency which frequency is uniquely representative of said wave signal receiver, a rotary switch rotatable with said step switching means for criodically interrupting the output circuit of said sec-- ond oscillator so as to cause it to produce periodic pulses of energy uniformly spaced with reference to time which spacing corresponds to the spacing between the steps of said step switching means, means responsive to the receipt of said heat frequency signal of said predetermined frequency during each cycle for biasing said second oscillator so that it is ineffective to produce said pulses during the remainder of cycle whereby the number of pulses produced during each cycle is representative of the particular tran tting station to which said wave signal rccoi er tuned, and means for producing a record of the output of said second oscillator.

' SERGE A. SCHERBATSI'IOY.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,249,32 Potter July 15, 1% 2,275,460 Page Mar. 10, 1942 2,344,562 Potter lfiar. 19% 2,418,139 Preisman Apr. 1, 1947 2,418,750 Bliss et al. Apr. 8, 1947 

